Chaco Canyon

Chaco Culture National Historical Park lies in north-western New Mexico, between the cities of Albuquerque and Farmington, in San Juan County. It covers 137 km2 and is surrounded by Navajo tribal land. The park is in the San Juan Basin, on the south-eastern edge of the Colorado Plateau, between several mountain ranges: the Chuska Mountains to the west, the San Juan Mountains to the north and the San Pedro Mountains to the east. The Chacoans obtained their timber in these mountains, including oak, pinyon pine, ponderosa pine and juniper.

The valley runs from north-west to south-east and is bordered by flat-topped landforms called mesas. The Chaco Wash, an intermittent stream fed by rainfall runoff, crosses the park for about 20 km, and its catchment covers 2 175 km2. The main complexes, such as Pueblo Bonito, Nuevo Alto and Kin Kletso, lie at altitudes between 1 890 metres and 1 963 metres. A shallow aquifer allowed the inhabitants to obtain water.

The park lies in a high desert and receives on average 231.1 mm of precipitation a year. A drought has affected the area since 2000, since when the average has fallen to 165 mm.

The Chacoans quarried sandstone blocks and carried timber over long distances to build fifteen building complexes that remained the largest in North America until the nineteenth century. The Great Houses of Chaco, built roughly between 850 and 1150 CE, stood at the centre of a wider ritual landscape of farming communities in the northern American Southwest.

Anasazi builders came down into the canyon to build in the tenth century. Peñasco Blanco was built between 900 and 1125, Chetro Ketl from 900, and Pueblo Bonito from 960, when a first section of fifty rooms was laid out in an arc. Some of the houses had six storeys. The roof beams, some of them five metres long and weighing 300 kg, came from forests more than 75 km away, in the Zuni and Chuska mountains, and were generally of ponderosa pine.